﻿
#include<iostream>
#include<assert.h>
#include<string.h>
using namespace std;


namespace my {
	class string{
public:
	typedef char* iterator;
	typedef const char* const_iterator;
	iterator begin(){
		return _str;
	}
	iterator end(){
		return _str + _size;
	}
	const_iterator begin() const{
		return _str;
	}
	const_iterator end() const{
		return _str + _size;
	}

	string(const char* str = "")
		:_size(strlen(str))
		, _capacity(_size)
	{
		cout << "string(char* str)-构造" << endl;
		_str = new char[_capacity + 1];
		strcpy(_str, str);
	}

	void swap(string& s){
		std::swap(_str, s._str);
		std::swap(_size, s._size);
		std::swap(_capacity, s._capacity);
	}

	string(const string& s)
		:_str(nullptr)
	{
		cout << "string(const string& s) -- 拷贝构造" << endl;
		reserve(s._capacity);
		for (auto ch : s){
			push_back(ch);
		}
	}

	// 移动构造
	string(string&& s){
		cout << "string(string&& s) -- 移动构造" << endl;
		swap(s);
	}

	string& operator=(const string& s){
		cout << "string& operator=(const string& s) -- 拷贝赋值" <<
			endl;
		if (this != &s){
			_str[0] = '\0';
			_size = 0;
			reserve(s._capacity);
			for (auto ch : s){
				push_back(ch);
			}
		}
		return *this;
	}
	// 移动赋值
	string& operator=(string&& s){
		cout << "string& operator=(string&& s) -- 移动赋值" << endl;
		swap(s);
		return *this;
	}

	~string(){
		//cout << "~string() -- 析构" << endl;
		delete[] _str;
		_str = nullptr;
	}

	char& operator[](size_t pos){
		assert(pos < _size);
		return _str[pos];
	}
	void reserve(size_t n){
		if (n > _capacity)
		{
			char* tmp = new char[n + 1];
			if (_str)
			{
				strcpy(tmp, _str);
				delete[] _str;
			}
			_str = tmp;
			_capacity = n;
		}
	}
	void push_back(char ch){
		if (_size >= _capacity){
			size_t newcapacity = _capacity == 0 ? 4 : _capacity * 2;
			reserve(newcapacity);
		}
		_str[_size] = ch;
		++_size;
		_str[_size] = '\0';
	}
	string& operator+=(char ch){
		push_back(ch);
		return *this;
	}
	const char* c_str() const{
		return _str;
	}
	
	size_t size() const{
		return _size;
	}
private:
	char* _str = nullptr;
	size_t _size = 0;
	size_t _capacity = 0;
};
}

